Method and system for recycling and treating dyeing wastewater

Abstract

A method and system for recycling and treating dyeing wastewater are provided. To begin with, the dyeing wastewater is added with an adsorbent for assisted decolorization and filtration. Then, the wastewater is filtered with a first filtration device having hydrophilic membranes. The liquid having passed through the hydrophilic membranes undergoes an RO membrane-base filtration process to produce recycled water and concentrated wastewater. The concentrated wastewater is delivered into a second filtration device having hydrophobic membranes, before a micro-bubbling process is performed on the concentrated wastewater in the second filtration device to turn the concentrated wastewater into a creamy-white nebulized working liquid of high gas content. The steam in the working liquid can readily pass through the hydrophobic membranes to produce an effluent that meets effluent standards.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to wastewater treatment methods and systems, and more particularly, to a method and system for recycling and treating dyeing wastewater efficiently and at low costs, wherein the method and system are effective in solving problems found with effluent chromaticity.[0003]2. Description of the Related Art[0004]As the dyeing industry requires the use of various dyes, surfactants, and chemical agents, dyeing wastewater is characterized by high chromaticity, marked variation in water quality, and low biodegradability. Therefore, dyeing wastewater has to be treated by both biological and chemical processes in order to reduce biochemical oxygen demand (BOD), chemical oxygen demand (COD), suspended solids (SS), and chromaticity of the dyeing wastewater.[0005]A conventional method employed by most dyeing factories in Taiwan to treat dyeing wastewater essentially comprises, as shown in FIG. 1, the step...

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Benefits of technology

[0008]It is an objective of the present invention to provide a method and system for recycling and treating dyeing wastewater efficiently and at low costs,

Problems solved by technology

These two treatment processes, however, end up with a large amount of sludge whose water content is so high that the sludge can only be dehydrated by distillation.

As a result, the conventional method for treating dyeing wastewater is energy-intensive and cost-incurring.

Besides, the chromaticity of the processed effluent is too high to meet the existing effluent chromaticity standard recommended by the American Dye Manufacturers Institute (ADMI).

Therefore, dyeing wastewater decolorization technology has become an environmental protection issue that draws attention from the dyeing industry.

However, as dyeing wastewater contains a large amount of suspended substances, if the dyeing wastewater does not undergo a proper pre-treatment process, the RO membranes are subject to concentration polarization and may produce oxidized crystals.

Even worse, the efficiency of filtration may dwindle to an inca

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